The Influence of Footwear Midsole Thickness on Running Economy and Frontal Plane Ankle Stability

Abstract Despite being an intricate part of advanced footwear technology, the impact of midsole thickness is not well understood. While some individuals have speculated an increased midsole thickness might bequeath an unfair performance advantage, others have suggested it may have a detrimental impact on frontal plane ankle stability. Therefore, the purpose of this study was to determine the influence of midsole thickness on running economy, and frontal plane ankle stability. Twenty one recreational runners (ten female, and eleven male) participated in this study, performing five-minute treadmill running trials in four footwear conditions. The footwear conditions were nearly identical except for their midsole thicknesses which ranged from 35- to 50-mm in increments of 5-mm. Midsole thickness was not found to influence the energetic cost of running however, it was found to decrease frontal plane ankle stability. Given these results World Athletic restrictions on midsole thickness may be unnecessary and worthy of reconsideration.